Boring tool



Feb. 4, 1936. H BERG 2,029,458

BORING TOOL Filed May 2,8, 1934 Snuentor HEP/VAN 35166 (Ittornegs Patented Feb. 4, 1936 UNITED BORING TOOL corporation of Ohio Application May 28, 1934, Serial No. 727,958

7 Claims.

This invention relates broadly to reamers or 'boring tools, and more specifically to improvements in mechanism for retaining a cutting tool in a boring bar stub arbor or analogous support.

The primary object of the invention is to provide a device for securing a cutting tool or holder therefor within the boring bar and to this end ythe invention contemplates an improved and simplified construction relative to prior known devices of this class. More specifically, the invention comprehends a tool clamping or locking device which may be readily adjusted to secure the cutter in operative position, the device being constructed to accommodate a minimum of travel or movement of the parts which effect the clamping action.

A further object of the invention is to produce a device which is so constructed to eliminate the danger of springing or breaking the parts of the assembly when adjusting the device into clamping position.

Another object of the invention is to construct a clamping device in which a self-cleaning or wiping action between certain parts thereof is effected during the adjusting action; and further a clamping or locking device wherein the parts are sturdy of construction and susceptible of economic manufacture and assembly.

Other objects and advantages more or less ancillary toY the foregoing reside in the specic construction and aggroupment of elements peculiar to the structure, as will become apparent from a more complete examination of this specification, in the claims whereof there are assembled certain combinations of parts and structure indicative of the scope and spirit of the invention.

In the drawing:

Figure 1 is an elevational view, partially in section, of a portion of a boringbar embodying the invention;

Figs. 2 and 3 are transverse sectional Views takenron planes indicated by the lines 2-2 and 3-3, respectively, Fig. 1;

Fig. 4 is a central longitudinal sectional View of the tool-clamping member; Fig. 5 is a view in rear elevation of said member; and Figs. 6, 7 and 8 are detail perspective views of parts of the tool-clamping assembly.

Referring to the drawing and particularly to Fig. 1 thereof, the boring bar 5 is formed with a rectangular slot 6 therein, the major axis thereof being in coaxial relation with the bar. Adjacent the slot 6 there is a threaded bore 'I in which adjusting screws 8 and 9 are mounted. The wall of the bar 5 intermediate the slot 6 and the bore 'I is centrally apertured or slotted, as at Ill, to receive a guide block or tongue I I, the latter being recessed or apertured, as at I2, to receive the shank-end portions of the adjusting screws 8 5 and 9. Slot I is of suitable width with respect to the tongue II to accommodate diametric adjustments of the tongue within the boring bar.

For the purposes of illustration, the cutting tool shown herein embodies a tool block I3 prol0 vided with a notch I4 in the forward edge thereof which is dimensioned to snugly engage the tongue I I. The tool bits or cutters I may be retained within the block I3 in any suitable manner, such as through the dove-tail connection shown, and may be adjusted radially with respect to the axis of the boring bar by set screws I6. The length of the slot 6 is proportioned relative to the tool block and locking device to permit the clamping engagement of the assembly against the end wall of the slot and upon release of the locking device the ready retraction of the tool block from the boring bar.

The locking device or clamping assembly comprises a clamping block Il, sliding end cam 25 blocks I8 and I8a, a resilient retracting member embodying a saddle-shaped leaf spring I9, a centering pin 2l), and draw bolt 2I. 'Ihe clamping block I'I is formed with a longitudinal slot or recess 22 in the face thereof in which a spring 30 I 9 is seated with the opposed ends thereof engaging the end portions of the slot, note Fig. 4. The clamping block is also formed with a transverse recess 23 through which pin 2D is passed, the curved central portion of spring I9 normally bearing against said pin. The rear wall of the block I'I is constructed with a longitudinal slot 2d for the reception of a draw bolt 2|. The latter is formed with a head 2 Ia having a socket 2 Ib therein configured to accommodate a socket 40 wrench or like tool.

The cam block I8 is formed with a counter bore 25 in which the head 2Ia of the bolt 2l is engaged, while the block I8a is tapped as at 26 for engagement with the threaded end of said bolt.

The extremities of the clamp block II are each formed with cam portions 21 and 27a adapted to coact With cam surfaces 28 formed on the blocks I8 and Ia. The cams 21a constitute the 50 clamping cams and are each relatively abrupt to a certain point and thereafter taper more gradually; thereby eifectuating an initial relatively short and rapid throw of the clamp block I1 toward the tool block I3 until the more gradually 55 tapered portion is reached, whereupon the throw becomes more gradual with greater leverage. When the block I's' is in its extreme retracted position, the surfaces 27 are contiguous to, or in contact with the surfaces 28.

The boring bar is provided with a set screw 29, note Fig. 2, which is disposed in one of the walls adjacent the slot 6. The end of this screw is formed to provide a detent coordinated for lengagement With a recess 3E] in the face of the tool holder I3 and loosely supports the cutter within the bar when the tongue II is disengaged with the notch I in block I3 and the cuttingL-tools are permitted to i'loat as in a reaming operation.

In assembly and operation,.i.the"cutting# tool, comprising the block I3 and bits I5, is mounted in the boring bar 5 with the clamping assembly in juxtaposition therewith aszshown in'lig.V 1.

Centralization of the cutting tool is eifected by the position of the tongue Il, or may` be varied -ifynecessary by adjusting the', screws 8 and 9. A suitable tool, orvsocket Vwrench is* then .inserted in socketgZIbv of the draw bolt 2! and the latter turned to'drawthe cam blocks I8 and AIta` toward Veach other-over the vcam surfaceslapthereby forcingthe clampingblock` I'I against the'tool block I3, the pinZil holding the block against lateral movement during this operation. To retract the block I'Lythe draw'bolt-ZI is loosened yand blocks1I8 and'l lctarefretracted, the spring IS'then 'forcing' the block I'I -back to clear the tongue' I I.

Itwill be'noted that the draw bolt 2l is threaded only -atfone endrwhile the headed endA 2m thereof engagesv the other cam block. 'Ihusethe 'cam blocks have in effect a floating camaction -on the 4block I'I. This construction, thoughv not ,deemed necessary is preferred inl practice since itensures,coaction ybetweenthe wedge blocks to the 'lim-,itof' the-clamping operation.

Thecontacti-ngcam'surfaces 21a and'28 are always 'maintainedclear of chips, since the forwardy rounded edge of each block. I8,`I8a wipes -an'dclears its coacting cam-surface when moving vthereover- Y YAlthough the foregoing description is necessarily of a detailed character in order that the inventionmay be completely set forth, itzis to be-understood that thespecic 4terminology is not intendedto be restrictive or conning,V and that ,variousrearrangementsof parts and modifications of structural detail maybe resortedrto without departing from the scope or spirit ofthe ,invention as ,hereinclaimed `I cla-im:

l. In:a boring or reaming tool assembly, aboring barhavingfaslot formed therethrough, a; tool .block mounteddnfsaidfslot, anda 'clamp-ing assembly positioned between the ytool block and adjacent end Wall of the slot; saideassembly com- ,prising a clamping block having an elongated ,face adapted to exert clamping pressure on the toolblock and .rear cam portions at. oppositeex- ,tremities thereof, cam blocksdisposed between said cam portions .and the adjacent end wallrof `the slot, Vand afdrawbolt connecting said cam fblocks for contracting the latter into engagement with the cam portions and thereby move the .clamping block into clamping position with revspectto .thertool block, each of said cam portions beingrelatively abrupt at its starting point to `eiectan initial relatively short and rapid throw ofthe clampingblock` and thereafter tapering off gradually toprovide greater leverage for the cam rear Vgroove portion, cam blocks disposed between 'thempposite extremities of the clamping block ,clamping 4assembly positioned between the: tool through, -atool block Vmounted insaid slot,.said ,boring bar rand block being formedlwith` aligned block and exert clamping pressure thereon, the 10 wclamping block being formed with a rear portion` having a longitudinal groove formed therein, cam Y `portions formed at opposite extremities of the clamping block between said face portion Vand and the adjacent end wall of the slot and adapted to actoonfs'aid cam portions, a draw bolt positionedin said longitudinal groove and connecting said cam blocks for contracting and expanding the latter, `means for anchoring-'the"clampingV blockY to the 4boring bar to hold' the Ablock against lateral'fdisplacement, and resilient means'associated with said anchoring means for retracting the clamping-block clear of the tool blockfupon g5 Y expansion of said cam blocks.

3. -In=aboring or reaming tool assembly, v'a bor- 'ing bar vhaving Aa slot formed therethrough, a

tool block mounted vin said slot, and a removable block and .Y adjacent'v end wallv ofthe slot; said assembly comprising `a clamping block having fan elongated face portion arranged lto .abut the tool f block and 'a longitudinally grooved rear portion,

the clamping blockl being `formed-with cam sur- '35 faces at opposite extremities thereofin rear-fof .said .face portion, cam blocks .disposed/between said. Caml-surfaces and the yadjacent end wall. of

the slot; a draw bolt mounted-in the longitudinal groove-formed in the clamping block-and-con- 14, necting the cam blocks forcontractingwand expanding theolatter to movethe clampingblock .into and release it from. clampingn pressure :with

respect vto the tool ublock, v.said Y clamping .,block beingrformed with aA longitudinalrecessinthe 1,45 face portionV thereof anda transverse.. recessintersecting saidlongitudinal recess,`4 av leaf spring mounted in `said longitudinal Vrecess,. and .an ran- ,chor pin mounted in said transverserlrecess, Jsaid spring straddling the anchor 4pin and serving-to 50 retract..1;he .clamping blocksrclear of the `tool `block upon. expansion of .said cam blocks. 'Y Y Yli. A `boring or-reaming toolassemblycomprising: Va boring bar having-a-slot-formed there recesses, a tongue mounted in said boring'bar and having a portion thereofextendingwithin 'the' said Vslotsand arranged for transaxialV adjust- Vment lrelatively' to 'the boring bar, -adjusting L60 screws mounted in said bar and adapted' toren- ;gage said tongue, the said tool block having a recess-in the marginal edge thereof'for receiving said tongue, a clamping assembly mounted inA said lslot intermediate the end wall thereof and Athe tool block, said clamping assembly comprising cam portions, the face portion of said clamping block being formed with a longitudinal recess, and a transverse recess intersecting said longitudinal recess, a pin passed through said transverse recess and anchored to the boring bar for holding the clamping block against tranverse displacement with respect to the tool block, and a saddle shaped leaf spring mounted in said longitudinal recess and straddling said pin.

5. In a boring or reaming tool assembly, a bor- Aing bar having a slot formed therethrough, a

tool block mounted in said slot, and a clamping assembly positioned between the tool block and the adjacent end wall of the slot; said assembly comprising a clamping block having an elongated face adapted to bear against the tool block and rear cam portions at opposite extremities thereof, cam blocks arranged to bear against said cam porti-ons, means for contracting and expanding said blocks to thereby move the clamping block into clamping position with respect to the tool block, means for anchoring the clamping block against displacement with respect to the boring bar, while permitting limited movement longitudinally of the latter, and a spring coacting with said anchoring means for urging the clamping block clear of the tool block when the cam blocks are expanded.

6. In a boring or reaming tool assembly, a boring bar having a slot formed therethrough, a tool block mounted in said slot, a guide block or tongue interposed between one end wall .of the slot and the tool block and engaging in an aperture formed in the toolblock, and a removable clamping assembly positioned between the tool block and the opposite end wall of the slot; said assembly comprising a clamping block adapted to exert clamping pressure on the tool block and having cam portions at opposite extremities thereof, cam blocks disposed between the said cam portions and adjacent end Wall of the slot, means for contracting said cam blocks to thereby move the clamping block into clamping position with respect to the tool block, means for anchoring the clamping block against lateral displacement with respect to the boring bar while permitting limited movement of said block longitudinally of the bar, and means co-acting with said anchoring means for retracting the clamping block from the tool block upon release of said cam blocks such distance as will permit the clamping block to clear said guide block or tongue.

'7. In a boring or reaming tool assembly, a boring bar0 having a slot formed therethrough, a tool block mounted in said slot, an adjustable guide block or tongue interposed between one end wall of the slot and the tool block and engaging in an aperture formed in the tool block, and a removable clamping assembly positioned between the tool block and adjacent end wall of the slot; said assembly comprising a clamping block adapted to exert clamping pressure on the tool block and having cam portions at opposite extremitiesA thereof, cam blocks disposed between said cam portions and the adjacent end wall of the slot, a draw bolt connecting said cam blocks for contracting and expanding the latter to thereby move the clamping block into and from clamping engagement with respect to the tool block, means for holding the clamping block against lateral movement with respect to the boring bar, and a spring coacting with said latter means for retracting the clamping block from the tool block upon expansion of said cam blocks such distance as will permit the clamping block to clear said guide block or tongue.

HERMAN BERG. 

